Enhanced power amplifier efficiency through elimination of matching network

ABSTRACT

Enhanced power amplifier efficiency through elimination of matching network. In some embodiments, a power amplification system can include a power amplifier (PA) configured to receive and amplify a radio-frequency (RF) signal, and an output filter coupled to the PA by an output path that is substantially free of an impedance transformation circuit. The PA can be further configured to drive approximately a characteristic load impedance of the output filter. The PA being configured to drive approximately the characteristic load impedance of the output filter can be effectuated by the PA being operated with a high-voltage (HV) supply.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority to U.S. Provisional Application No.62/116,448 filed Feb. 15, 2015, entitled REDUCED POWER AMPLIFIER SIZETHROUGH ELIMINATION OF MATCHING NETWORK, U.S. Provisional ApplicationNo. 62/116,449 filed Feb. 15, 2015, entitled ENHANCED POWER AMPLIFIEREFFICIENCY THROUGH ELIMINATION OF MATCHING NETWORK, U.S. ProvisionalApplication No. 62/116,450 filed Feb. 15, 2015, entitled MULTI-BANDPOWER AMPLIFICATION SYSTEM HAVING ENHANCED EFFICIENCY THROUGHELIMINATION OF BAND SELECTION SWITCH, and U.S. Provisional ApplicationNo. 62/116,451 filed Feb. 15, 2015, entitled MULTI-BAND DEVICE HAVINGMULTIPLE MINIATURIZED SINGLE-BAND POWER AMPLIFIERS, the disclosure ofeach of which is hereby expressly incorporated by reference herein inits entirety.

BACKGROUND

1. Field

The present disclosure generally relates to power amplifiers forradio-frequency (RF) applications.

2. Description of the Related Art

In radio-frequency (RF) applications, an RF signal to be transmitted istypically generated by a transceiver. Such an RF signal can then beamplified by a power amplifier (PA), and the amplified RF signal can berouted to an antenna for transmission.

SUMMARY

According to a number of implementations, the present disclosure relatesto a power amplification system that includes a power amplifier (PA)configured to receive and amplify a radio-frequency (RF) signal, and afilter coupled to the PA and configured to condition the amplified RFsignal. The PA is further configured to drive approximately acharacteristic load impedance of the filter.

In some embodiments, the PA can have an impedance that is greater thanapproximately 40 Ohms. The impedance of the PA can have a value ofapproximately 50 Ohms.

In some embodiments, power amplification system can further include asupply system configured to provide a high-voltage (HV) supply to thePA. The supply system can include a boost DC/DC converter configured togenerate the HV supply based on a battery voltage Vbatt.

In some embodiments, the PA can include a heterojunction bipolartransistor (HBT). The HBT can be, for example, a gallium arsenide (GaAs)device. The HV supply can be provided to a collector of the HBT as VCC.

In some embodiments, the filter can be a transmit (Tx) filter configuredto operate in a corresponding Tx frequency band. The Tx filter can bepart of a duplexer configured to operate in the Tx frequency band and acorresponding receive (Rx) frequency band.

In some embodiments, the filter can be coupled to the PA by an outputpath that is substantially free of an impedance transformation circuit.

In some embodiments, the power amplification system can further includeone or more additional PAs, with each being configured to operate withthe HV supply and amplify a corresponding RF signal. The poweramplification system can further include a filter coupled to each of theone or more additional PAs and configured to condition the correspondingamplified RF signal. Each of the one or more additional PAs can befurther configured to drive approximately a characteristic loadimpedance of the corresponding filter. Each of the one or moreadditional filters can be coupled to the corresponding PA by an outputpath that is substantially free of an impedance transformation circuit.

In some embodiments, the PA and the one or more additional PAs can formM PAs. In some embodiments, the M PAs can be implemented on a singlesemiconductor die. The M PAs can be configured to operate in separatefrequency bands. The system can be substantially free of a bandselection switch between the M PAs and their corresponding filters.

In some embodiments, the power amplification system can be configured tooperate as an average power tracking (APT) system. The APT system canhave a lower loss than another power amplifier system having similarband handling capability but in which the PAs are operated in lowvoltage. The other power amplifier system can be an envelope tracking(ET) system. The APT system can have an overall efficiency that isgreater than an overall efficiency of the ET system.

In some teachings, the present disclosure relates to a radio-frequency(RF) module that includes a packaging substrate configured to receive aplurality of components, and a power amplification system implemented onthe packaging substrate. The power amplification system includes aplurality of power amplifiers (PAs), with each PA being configured toreceive and amplify a radio- frequency (RF) signal. The poweramplification system further includes a filter coupled to each PA thatis configured to drive approximately a characteristic load impedance ofthe filter.

In some embodiments, each PA can be configured to operate in ahigh-voltage (HV) supply mode. Each filter can be coupled to thecorresponding PA by an output path that is substantially free of animpedance transformation circuit.

In some embodiments, the RF module can be substantially free of a bandselection switch between the plurality of PAs and their correspondingfilters. In some embodiments, the RF module can be, for example, afront-end module (FEM).

According to some implementations, the present disclosure relates to awireless device that includes a transceiver configured to generate aradio-frequency (RF) signal, and a front-end module (FEM) incommunication with the transceiver. The FEM includes a packagingsubstrate configured to receive a plurality of components, and a poweramplification system implemented on the packaging substrate. The poweramplification system includes a plurality of power amplifiers (PAs),with each PA being configured to receive and amplify a radio-frequency(RF) signal. The power amplification system further includes a filtercoupled to each PA that is configured to drive approximately acharacteristic load impedance of the filter. The wireless device furtherincludes an antenna in communication with the FEM, with the antennabeing configured to transmit the amplified RF signal.

In some teachings, the present disclosure relates to a method forprocessing a radio-frequency (RF) signal. The method includes amplifyingthe RF signal with a power amplifier (PA), and routing the amplified RFsignal to a filter. The method further includes operating the PA suchthat the PA drives approximately a characteristic impedance of thefilter.

In some embodiments, the PA can have an impedance that is approximately50 Ohms. In some embodiments, operating the PA can include supplying thePA with a high-voltage (HV).

In accordance with a number of teachings, the present disclosure relatesto a power amplification system that includes a power amplifier (PA)configured to receive and amplify a radio-frequency (RF) signal. Thepower amplification system further includes an output filter coupled tothe PA by an output path that is substantially free of an impedancetransformation circuit.

In some embodiments, the PA can be further configured to driveapproximately a characteristic load impedance of the output filter. ThePA being configured to drive approximately the characteristic loadimpedance of the output filter can be effectuated by the PA beingoperated with a high-voltage (HV) supply. The output path beingsubstantially free of an impedance transformation circuit can result ina reduction in loss by at least 0.5 dB between the PA and the outputfilter.

In some embodiments, the PA can have an impedance that is greater thanapproximately 40 Ohms. The impedance of the PA can have a value ofapproximately 50 Ohms. The impedance of the PA can result in a reducedcurrent drain in the PA. The reduced current drain in the PA can allowthe PA to be dimensioned smaller than another PA having a lowerimpedance.

In some embodiments, the power amplification system can further includea supply system configured to provide a high-voltage (HV) supply to thePA. The supply system can include a boost DC/DC converter configured togenerate the HV supply based on a battery voltage Vbatt.

In some embodiments, the PA can include a heterojunction bipolartransistor (HBT). The HBT can be a gallium arsenide (GaAs) device. TheHV supply can be provided to a collector of the HBT as VCC.

In some embodiments, the output filter can be a transmit (Tx) filterconfigured to operate in a corresponding Tx frequency band. The Txfilter can be part of a duplexer configured to operate in the Txfrequency band and a corresponding receive (Rx) frequency band.

In some embodiments, the power amplification system can further includeone or more additional PAs, with each being configured to operate withthe HV supply and amplify a corresponding RF signal. The poweramplification system can further include an output filter coupled toeach of the one or more additional PAs by an output path that issubstantially free of an impedance transformation circuit. Each of theone or more additional PAs can be further configured to driveapproximately a characteristic load impedance of the correspondingoutput filter.

In some embodiments, the PA and the one or more additional PAs can formM PAs. The M PAs can be implemented on a single semiconductor die. The MPAs can be configured to operate in separate frequency bands.

In some embodiments, the power amplification system can be substantiallyfree of a band selection switch between the M PAs and theircorresponding output filters. The power amplification system beingsubstantially free of a band selection switch can result in a reductionin loss by at least 0.3 dB between a given PA and the correspondingoutput filter.

In some embodiments, the power amplification system can be configured tooperate as an average power tracking (APT) system. The APT system canhave a lower loss than another power amplifier system having similarband handling capability but in which the PAs are operated in lowvoltage. The other power amplifier system can be an envelope tracking(ET) system. The APT system can have an overall efficiency that isgreater than an overall efficiency of the ET system.

According to some implementations, the present disclosure relates to aradio-frequency (RF) module that includes a packaging substrateconfigured to receive a plurality of components, and a poweramplification system implemented on the packaging substrate. The poweramplification system includes a plurality of power amplifiers (PAs),with each PA being configured to receive and amplify a radio-frequency(RF) signal. The power amplification system further includes an outputfilter coupled to each of the PAs by an output path that issubstantially free of an impedance transformation circuit.

In some embodiments, each PA can be configured to operate in ahigh-voltage (HV) supply mode. Each PA can be further configured todrive approximately a characteristic load impedance of the correspondingoutput filter.

In some embodiments, the RF module can be substantially free of a bandselection switch between the plurality of PAs and their correspondingoutput filters. The RF module can be, for example, a front-end module(FEM).

In some implementations, the present disclosure relates to a wirelessdevice that includes a transceiver configured to generate aradio-frequency (RF) signal, and a front-end module (FEM) incommunication with the transceiver. The FEM includes a packagingsubstrate configured to receive a plurality of components, and a poweramplification system implemented on the packaging substrate. The poweramplification system includes a plurality of power amplifiers (PAs),with each PA being configured to receive and amplify a radio-frequency(RF) signal. The power amplification system further includes an outputfilter coupled to each of the PAs by an output path that issubstantially free of an impedance transformation circuit. The wirelessdevice further includes an antenna in communication with the FEM, withthe antenna being configured to transmit the amplified RF signal.

In some teachings, the present disclosure relates to a method forprocessing a radio-frequency (RF) signal. The method includes amplifyingthe RF signal with a power amplifier (PA), and routing the amplified RFsignal to an output filter substantially without impedancetransformation. The method further includes filtering the amplified RFsignal with the output filter.

In some embodiments, amplifying the RF signal can include operating thePA such that the PA drives approximately a characteristic impedance ofthe output filter to allow the routing substantially without theimpedance transformation. The PA can have an impedance that isapproximately 50 Ohms. In some embodiments, operating the PA can includesupplying the PA with a high- voltage (HV).

In accordance with some teachings, the present disclosure relates to apower amplification system that includes a plurality of power amplifiers(PAs), with each PA being configured to receive and amplify aradio-frequency (RF) signal in a frequency band. The power amplificationsystem can further include an output filter coupled to each of the PAsby a separate output path such that the power amplification system issubstantially free of a band selection switch between the plurality ofPAs and their corresponding output filters.

In some embodiments, each of the PAs can be further configured to driveapproximately a characteristic load impedance of the correspondingoutput filter. Each PA being configured to drive approximately thecharacteristic load impedance of the corresponding output filter can beeffectuated by the PA being operated with a high-voltage (HV) supply.The power amplification system being substantially free of the bandselection switch can result in a reduction in loss by at least 0.3 dBbetween each PA and the corresponding output filter.

In some embodiments, each PA can have an impedance that is greater thanapproximately 40 Ohms. The impedance of each PA can have a value ofapproximately 50 Ohms. The impedance of each PA results in a reducedcurrent drain in the PA. The reduced current drain in each PA can allowthe PA to be dimensioned smaller than another PA having a lowerimpedance.

In some embodiments, the power amplification system can further includea supply system configured to provide a high-voltage (HV) supply to eachPA. The supply system can include a boost DC/DC converter configured togenerate the HV supply based on a battery voltage Vbatt.

In some embodiments, each PA can include a heterojunction bipolartransistor (HBT). The HBT can be a gallium arsenide (GaAs) device. TheHV supply can be provided to a collector of the HBT as VCC.

In some embodiments, each output filter can be a transmit (Tx) filterconfigured to operate in a corresponding Tx frequency band. The Txfilter can be part of a duplexer configured to operate in the Txfrequency band and a corresponding receive (Rx) frequency band.

In some embodiments, each output filter can be coupled to thecorresponding PA by an output path that is substantially free of animpedance transformation circuit. Each output path being substantiallyfree of an impedance transformation circuit can result in a reduction inloss by at least 0.5 dB between the corresponding PA the output filter.

In some embodiments, the plurality of PAs can be implemented on a singlesemiconductor die. In some embodiments, the power amplification systemcan be configured to operate as an average power tracking (APT) system.The APT system can have a lower loss than another power amplifier systemhaving similar band handling capability but in which the PAs areoperated in low voltage. The other power amplifier system can be anenvelope tracking (ET) system. The APT system can have an overallefficiency that is greater than an overall efficiency of the ET system.

In some teachings, the present disclosure relates to a radio-frequency(RF) module having a packaging substrate configured to receive aplurality of components, and a power amplification system implemented onthe packaging substrate. The power amplification system includes aplurality of power amplifiers (PAs), with each PA being configured toreceive and amplify a radio-frequency (RF) signal in a frequency band.The power amplification system further includes an output filter coupledto each of the PAs by a separate output path such that the poweramplification system is substantially free of a band selection switchbetween the plurality of PAs and their corresponding output filters.

In some embodiments, each PA can be configured to operate in ahigh-voltage (HV) supply mode. Each PA can be further configured todrive approximately a characteristic load impedance of the correspondingoutput filter.

In some embodiments, each output path can be substantially free of animpedance transformation circuit between the corresponding PA and outputfilter. In some embodiments, the RF module can be a front-end module(FEM).

According to a number of teachings, the present disclosure relates to awireless device that includes a transceiver configured to generate aradio- frequency (RF) signal, and a front-end module (FEM) incommunication with the transceiver. The FEM includes a packagingsubstrate configured to receive a plurality of components, and a poweramplification system implemented on the packaging substrate. The poweramplification system includes a plurality of power amplifiers (PAs),with each PA being configured to receive and amplify a radio- frequency(RF) signal in a frequency band. The power amplification system furtherincludes an output filter coupled to each of the PAs by a separateoutput path such that the power amplification system is substantiallyfree of a band selection switch between the plurality of PAs and theircorresponding output filters. The wireless device further includes anantenna in communication with the FEM, with the antenna being configuredto transmit the amplified RF signal.

In some teachings, the present disclosure relates to a method forprocessing a radio-frequency (RF) signal. The method includes amplifyingthe RF signal with a selected one of a plurality of power amplifiers(PAs), with the RF signal being in a frequency band. The method furtherincludes routing the amplified RF signal to an output filtersubstantially without a band-selection switching operation. The methodfurther includes filtering the amplified RF signal with the outputfilter.

In some embodiments, amplifying the RF signal can include operating theselected PA such that the PA drives approximately a characteristicimpedance of the corresponding output filter to allow the routingsubstantially without an impedance transformation. The PA can have animpedance that is approximately 50 Ohms.

In some embodiments, operating the PA can include supplying the PA witha high-voltage (HV).

In some implementations, the present disclosure relates to a poweramplifier die that includes a semiconductor substrate a plurality ofpower amplifiers (PAs) implemented on the semiconductor substrate. EachPA is configured to drive approximately a characteristic load impedanceof a downstream component along an individual frequency band signalpath. Each PA is sized smaller than a wide band PA configured to drivemore than one of the frequency bands associated with the plurality ofPAs.

In some embodiments, the downstream component can include an outputfilter. The individual frequency band signal path can be a narrow bandsignal path. Each of the PAs being configured to drive approximately thecharacteristic load impedance of the corresponding output filter can beeffectuated by the PA being operated with a high-voltage (HV) supply.Each PA can have an impedance that is greater than approximately 40Ohms. The impedance of each PA can have a value of approximately 50Ohms. The impedance of each PA can result in a reduced current drain inthe PA. The reduced current drain in each PA can allow the PA to bedimensioned smaller than another PA having a lower impedance.

In some embodiments, each PA can include a heterojunction bipolartransistor (HBT) such as a gallium arsenide (GaAs) device. The HBT canbe configured to receive the HV supply through its collector as VCC.

In some embodiments, the PAs can be configured to operate in an averagepower tracking (APT) mode. The APT mode can result in a lower loss thananother die having similar band handling capability but in which the PAsare operated in low voltage. The other die can be configured to operatein an envelope tracking (ET) mode. The APT mode can yield an overallefficiency that is greater than an overall efficiency of associated withthe ET.

According to some implementations, the present disclosure relates to aradio-frequency (RF) module that includes a packaging substrateconfigured to receive a plurality of components, and a poweramplification system implemented on the packaging substrate. The poweramplification system includes a plurality of power amplifiers (PAs)implemented on a semiconductor substrate. Each PA is configured to driveapproximately a characteristic load impedance of a downstream componentalong an individual frequency band signal path. Each PA is sized smallerthan a wide band PA configured to drive more than one of the frequencybands associated with the plurality of PAs.

In some embodiments, each PA can be configured to operate in ahigh-voltage (HV) supply mode. In some embodiments, the downstreamcomponent can include an output filter. The output filter can be coupledto the corresponding PA by a separate output path such that the poweramplification system is substantially free of a band selection switchbetween the plurality of PAs and their corresponding output filters.Each output path can be substantially free of an impedancetransformation circuit between the corresponding PA and output filter.The RF module can be, for example, a front-end module (FEM).

In some teachings, the present disclosure relates to a wireless devicethat includes a transceiver configured to generate a radio-frequency(RF) signal, and a front-end module (FEM) in communication with thetransceiver. The FEM includes a packaging substrate configured toreceive a plurality of components, and a power amplification systemimplemented on the packaging substrate. The power amplification systemincludes a plurality of power amplifiers (PAs) implemented on asemiconductor substrate, with each PA being configured to driveapproximately a characteristic load impedance of a downstream componentalong an individual frequency band signal path. Each PA is sized smallerthan a wide band PA configured to drive more than one of the frequencybands associated with the plurality of PAs. The wireless device furtherincludes an antenna in communication with the FEM, with the antennabeing configured to transmit an amplified RF signal.

In some implementations, the present disclosure relates to a method forprocessing a radio-frequency (RF) signal. The method includes amplifyingthe RF signal with a selected one of a plurality of power amplifiers(PAs), with the selected PA driving approximately a characteristic loadimpedance of a downstream component along an individual frequency bandsignal path. The selected PA is sized smaller than a wide band PAconfigured to drive more than one of the frequency bands associated withthe plurality of PAs. The method further includes routing the amplifiedRF signal to the downstream component.

In some embodiments, the downstream component can include an outputfilter. Amplifying the RF signal can include supplying the selected PAwith a high-voltage (HV).

In accordance with some teachings, the present disclosure relates to amethod for fabricating a power amplifier die. The method includesforming or providing a semiconductor substrate, and implementing aplurality of individual frequency band signal paths. The method furtherincludes forming a plurality of power amplifiers (PAs) on thesemiconductor substrate, with each PA being configured to driveapproximately a characteristic load impedance of a downstream componentalong the corresponding individual frequency band signal path. Each PAis sized smaller than a wide band PA configured to drive more than oneof the frequency bands associated with the plurality of PAs.

For purposes of summarizing the disclosure, certain aspects, advantagesand novel features of the inventions have been described herein. It isto be understood that not necessarily all such advantages may beachieved in accordance with any particular embodiment of the invention.Thus, the invention may be embodied or carried out in a manner thatachieves or optimizes one advantage or group of advantages as taughtherein without necessarily achieving other advantages as may be taughtor suggested herein.

The present disclosure relates to U.S. patent application Ser. No.______ [Attorney Docket 75900-50182US1], entitled REDUCED POWERAMPLIFIER SIZE THROUGH ELIMINATION OF MATCHING NETWORK, U.S. patentapplication Ser. No. ______ [Attorney Docket 75900-50182US3], entitledMULTI-BAND POWER AMPLIFICATION SYSTEM HAVING ENHANCED EFFICIENCY THROUGHELIMINATION OF BAND SELECTION SWITCH, and U.S. patent application Ser.No. ______ [Attorney Docket 75900-50182US4], entitled MULTI-BAND DEVICEHAVING MULTIPLE MINIATURIZED SINGLE-BAND POWER AMPLIFIERS, thedisclosure of each of which is filed on even date herewith and herebyincorporated by reference herein in its entirety.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a wireless system or architecture having an amplificationsystem.

FIG. 2 shows that the amplification system of FIG. 1 can include aradio-frequency (RF) amplifier assembly having one or more poweramplifiers (PAs).

FIGS. 3A-3E show non-limiting examples of how each PA of FIG. 2 can beconfigured.

FIG. 4 shows that in some embodiments, the amplification system of FIG.2 can be implemented as a high-voltage (HV) power amplification system.

FIG. 5 shows that in some embodiments, the HV power amplification systemof FIG. 4 can be configured to operate in an average power tracking(APT) mode.

FIG. 6 shows an example envelope tracking (ET) power amplificationsystem.

FIG. 7 shows an example high-voltage (HV) average power tracking (APT)power amplification system having one or more features as describedherein.

FIG. 8 shows an HV APT power amplification system that can be a morespecific example of the HV APT power amplification system of FIG. 7.

FIG. 9 shows example efficiency plots as a function of output power, forpower amplifiers operated in Buck ET, Buck APT, and Boost APTconfigurations.

FIG. 10 shows that a power amplification system having one or morefeatures as described herein can have collector efficiency andpower-added efficiency (PAE) profiles that are similar to nominal cases.

FIG. 11 shows that a power amplification system having one or morefeatures as described herein can have linearity performance that issimilar to a nominal case.

FIG. 12 shows example plots of power amplifier load current as afunction of load voltage.

FIG. 13 shows an example where a power amplification system having oneor more features as described herein can yield one or more advantageousbenefits.

FIG. 14 shows another example where a power amplification system havingone or more features as described herein can yield one or moreadvantageous benefits.

FIG. 15 shows yet another example where a power amplification systemhaving one or more features as described herein can yield one or moreadvantageous benefits.

FIG. 16 shows yet another example where a power amplification systemhaving one or more features as described herein can yield one or moreadvantageous benefits.

FIG. 17 shows that in some embodiments, some or all of an HV APT poweramplification system having one or more features as described herein canbe implemented in a module.

FIG. 18 depicts an example wireless device having one or moreadvantageous features described herein.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

The headings provided herein, if any, are for convenience only and donot necessarily affect the scope or meaning of the claimed invention.

Introduction:

Referring to FIG. 1, one or more features of the present disclosuregenerally relate to a wireless system or architecture 50 having anamplification system 52. In some embodiments, the amplification system52 can be implemented as one or more devices, and such device(s) can beutilized in the wireless system/architecture 50. In some embodiments,the wireless system/architecture 50 can be implemented in, for example,a portable wireless device. Examples of such a wireless device aredescribed herein.

FIG. 2 shows that the amplification system 52 of FIG. 1 can include aradio-frequency (RF) amplifier assembly 54 having one or more poweramplifiers (PAs). In the example of FIG. 2, three PAs 60 a-60 c aredepicted as forming the RF amplifier assembly 54. It will be understoodthat other numbers of PA(s) can also be implemented. It will also beunderstood that one or more features of the present disclosure can alsobe implemented in RF amplifier assemblies having other types of RFamplifiers.

In some embodiments, the RF amplifier assembly 54 can be implemented onone or more semiconductor die, and such die can be included in apackaged module such as a power amplifier module (PAM) or a front-endmodule (FEM). Such a packaged module is typically configured to bemounted on a circuit board associated with, for example, a portablewireless device.

The PAs (e.g., 60 a-60 c) in the amplification system 52 can betypically biased by a bias system 56. Further, supply voltages for thePAs can be typically provided by a supply system 58. In someembodiments, either or both of the bias system 56 and the supply system58 can be included in the foregoing packaged module having the RFamplifier assembly 54.

In some embodiments, the amplification system 52 can include a matchingnetwork 62. Such a matching network can be configured to provide inputmatching and/or output matching functionalities for the RF amplifierassembly 54.

For the purpose of description, it will be understood that each PA (60)of FIG. 2 can be implemented in a number of ways. FIGS. 3A-3E shownon-limiting examples of how such a PA can be configured. FIG. 3A showsan example PA having an amplifying transistor 64, where an input RFsignal (RF_in) is provided to a base of the transistor 64, and anamplified RF signal (RF_out) is output through a collector of thetransistor 64.

FIG. 3B shows an example PA having a plurality of amplifying transistors(e.g., 64 a, 64 b) arranged in stages. An input RF signal (RF_in) isshown to be provided to a base of the first transistor 64 a, and anamplified RF signal from the first transistor 64 a is shown to be outputthrough its collector. The amplified RF signal from the first transistor64 a is shown to be provided to a base of the second transistor 64 b,and an amplified RF signal from the second transistor 64 b is shown tobe output through its collector to thereby yield an output RF signal(RF_out) of the PA.

In some embodiments, the foregoing example PA configuration of FIG. 3Bcan be depicted as two or more stages as shown in FIG. 3C. The firststage 64 a can be configured as, for example, a driver stage; and thesecond stage 64 b can be configured as, for example, an output stage.

FIG. 3D shows that in some embodiments, a PA can be configured as aDoherty PA. Such a Doherty PA can include amplifying transistors 64 a,64 b configured to provide carrier amplification and peakingamplification, respectively, of an input RF signal (RF_in), to yield anamplified output RF signal (RF_out). The input RF signal can be splitinto the carrier portion and the peaking portion by a splitter. Theamplified carrier and peaking signals can be combined to yield theoutput RF signal by a combiner.

FIG. 3E shows that in some embodiments, a PA can be implemented in acascode configuration. An input RF signal (RF_in) can be provided to abase of the first amplifying transistor 64 a operated as a commonemitter device. The output of the first amplifying transistor 64 a canbe provided through its collector and be provided to an emitter of thesecond amplifying transistor 64 b operated as a common base device. Theoutput of the second amplifying transistor 64 b can be provided throughits collector so as to yield an amplified output RF signal (RF_out) ofthe PA.

In the various examples of FIGS. 3A-3E, the amplifying transistors aredescribed as bipolar junction transistors (BJTs) such as heterojunctionbipolar transistors (HBTs). It will be understood that one or morefeatures of the present disclosure can also be implemented in or withother types of transistors such as field-effect transistors (FETs).

FIG. 4 shows that in some embodiments, the amplification system 52 ofFIG. 2 can be implemented as a high-voltage (HV) power amplificationsystem 100. Such a system can include an HV power amplifier assembly 54configured to include HV amplification operation for some or all of thePAs (e.g., 60 a-60 c). As described herein, such PAs can be biased by abias system 56. In some embodiments, the foregoing HV amplificationoperation can be facilitated by an HV supply system 58. In someembodiments, an interface system 72 can be implemented to provideinterface functionalities between the HV power amplifier assembly 54 andeither or both of the bias system 56 and the HV supply system 58.

Examples Related to HV APT Systems:

Many wireless devices such as cellular handsets are configured tosupport multiple frequency bands; and such devices typically requireand/or complex power amplification architectures. However, suchcomplexity in power amplification architectures can result indegradation of transmit efficiency as the number of supported bandsincreases. Such a degradation in efficiency can be due to, for example,increased loss incurred by combining of multiple frequency bands whilemaintaining competitive size and cost targets.

In some radio-frequency (RF) applications, portable transmit solutionscan include a battery voltage (e.g., 3.8V) power amplifier (PA) combinedwith a Buck switching power supply. In such an example approach, maximumtransmit power is typically achieved at the 3.8V battery voltage, whichtypically requires or utilizes a 13:1 impedance transformation networkwithin the PA to support, for example, a nearly 1.5 watt peak powerlevel.

In the foregoing example, efficiency improvement at lower transmit powerlevels can be supported by implementing a Buck power supply at voltagesbelow the battery voltage. Multi-band operation can be accomplishedusing an RF switch to select a desired filter corresponding to a desiredfrequency band. It is noted that some or all of the Buck power supply,the impedance transformation network and the RF switch can contribute toloss, which in turn reduces the transmit efficiency.

Some wireless systems can include an envelope-tracking (ET) featureimplemented into a Buck supply to provide an increase in systemefficiency. However, envelope tracking can increase the cost of the Buckswitching supply, and can also significantly complicate the systemcharacterization and calibration process.

Described herein are examples of systems, circuits, devices and methodsthat can significantly reduce loss while maintaining or improvingcompetitive levels of size and/or cost. FIG. 5 shows that in someembodiments, the HV power amplification system 100 of FIG. 4 can beconfigured to operate in an average power tracking (APT) mode. In theexample of FIG. 5, an HV APT power amplification system 100 can includea power amplifier assembly 104 having one or more PAs configured toamplify one or more RF signals (RF_In). Such amplified RF signal(s) canbe routed to a duplexer assembly 108 having one or more duplexers,through a match component 106 having one or more matching circuits.

The duplexer(s) can allow duplexing of transmit (Tx) and receive (Rx)operations. The Tx portion of such duplexing operations is depicted asone or more amplified RF signals (RF_Out) being output from the duplexerassembly 108 for transmission through an antenna (not shown). In theexample of FIG. 5, the Rx portion is not shown; however, receivedsignals from an antenna can be received by the duplexer assembly 108 andoutput to, for example, low-noise amplifiers (LNAs).

Various examples are described herein in the context of Tx and Rxoperations utilizing duplexers, and such duplexers can facilitate, forexample, frequency-division duplexing (FDD) functionality. It will beunderstood that in some embodiments, an HV power amplification systemhaving one or more features as described herein can also be implementedin other duplexing configurations, including, for example, time-divisionduplexing (TDD) configuration.

In the example of FIG. 5, an HV supply system 102 is shown to provideone or more HV supply signals to the power amplifier assembly 104. Morespecific examples of how such HV signal(s) can be provided tocorresponding PA(s) are described herein in greater detail.

In some embodiments, the HV APT power amplification system 100 of FIG. 5can be configured to operate in an APT mode and meet or exceedperformance provided by envelope tracking (ET) implementations, whilemaintaining or reducing cost and/or complexity. In some embodiments,such an HV APT power amplification system can utilize high-voltagecapability of some PAs such as, for example, gallium arsenide (GaAs)heterojunction bipolar transistor (HBT) PAs. It will be understood thatone or more features of the present disclosure can also be implementedwith other types of PAs. For example, amplification systems utilizingCMOS devices with LDMOS multiple cascode stages, silicon bipolardevices, and GaN/HEMT devices can also benefit from operation inhigh-voltage regions.

With such HV operation of PAs, one or more lossy components can beeliminated from an amplification system, and/or other advantageousbenefit(s) can be realized. For example, PA output matching network(s)can be eliminated. In another example, PA supply efficiency can beincreased. In yet another example, some passive components can beremoved. Examples related to the foregoing are described herein ingreater detail.

One or more of the foregoing features associated with HV operation canresult in one or more die being implemented in smaller dimensions,thereby allowing greater flexibility in power amplification systemdesigns. For example, a power amplification system can be implementedwith an increased number of relatively small PAs, to thereby allowelimination of lossy components such as band switches. Examples relatedto such elimination of band switches are described herein in greaterdetail.

In some embodiments, the HV APT power amplification system 100 of FIG. 5can be configured so as to substantially eliminate or reducecomplexities associated with envelope tracking characterization and/orcalibration processes.

For the purpose of description, it will be understood that high-voltage(HV) can include voltage values that are higher than a battery voltageutilized in portable wireless devices. For example, an HV can be greaterthan 3.7V or 4.2V. In some situations, an HV can include voltage valuesthat are greater than a battery voltage and at which portable wirelessdevices can operate more efficiently. In some situations, an HV caninclude voltage values that are greater than a battery voltage and lessthan a breakdown voltage associated with a given type of PA. In theexample context of GaAs HBT, such a breakdown voltage can be in a rangeof 15V to 25V. Accordingly, an HV for GaAs HBT PA can be in a range of,for example, 3.7V to 25V, 4.2V to 20V, 5V to 15V, 6V to 14V, 7V to 13V,or 8V to 12V.

FIGS. 6 and 7 show a comparison between an envelope tracking (ET) poweramplification system 110 (FIG. 6) and a high-voltage (HV) average powertracking (APT) power amplification system 100 (FIG. 7) to demonstratehow some lossy components can be substantially eliminated in the HV APTpower amplification system 100. For the purpose of comparison, it willbe assumed that each power amplification system is configured to provideamplification for three frequency bands. However, it will be understoodthat more or less numbers of frequency bands can be utilized.

In the example of FIG. 6, the ET power amplification system 110 is shownto include a power amplifier assembly 114 having a broadbandamplification path 130 capable of providing amplification for threefrequency bands. The amplification path 130 can receive an input RFsignal through a common input node 126, and such an RF signal can berouted to one or more amplification stages through, for example, aDC-block capacitance 128. The amplification stages can include, forexample, a driver stage 132 and an output stage 134. In someembodiments, the amplification stages 132, 134 can include, for example,HBT or CMOS amplification transistors.

In the example of FIG. 6, the collector of the output stage 134 is shownto be provided with a supply voltage VCC from an envelope tracking (ET)modulator 122 through a choke inductance 124. The ET modulator 122 isdepicted as being part of an ET modulation system 112. The supplyvoltage VCC provided by such an ET modulator is typically determined ina dynamic manner, and can have a value in a range of, for example, about1V to 3V. The ET modulator 122 is shown to generate such a dynamic VCCvoltage based on a battery voltage Vbatt.

When the amplification path 130 is operated in the foregoing manner, itsimpedance Z is relatively low (e.g., about 3 to 5 Ω); and thus,impedance transformation typically needs to occur to match withimpedance associated with a downstream component. In the example of FIG.6, a band switch 138 (depicted as being part of a band switch system118) that receives the output of the amplification path 130 is typicallyconfigured as a 50 Ω load. Accordingly, and assuming that the impedance(Z) presented by the amplification path 130 is about 4 Ω, an impedancetransformation of about 13:1 (50:4) needs to be implemented. In theexample of FIG. 6, such an impedance transformation is shown to beimplemented by an output matching network (OMN) 136 which is depicted asbeing part of a load transform system 116.

In the example of FIG. 6, the band switch 138 is depicted as having asingle input from the output of the amplification path 130 (through theOMN 136), and three outputs corresponding to three example frequencybands. Three duplexers 142 a-142 c are shown to be provided for suchthree frequency bands.

Each of the three duplexers 142 a-142 c is shown to include TX and RXfilters (e.g., bandpass filters). Each TX filter is shown to be coupledto the band switch 138 to receive the corresponding amplified andswitch-routed RF signal for transmission. Such an RF signal is shown tobe filtered and routed to an antenna port (ANT) (144 a, 144 b or 144 c).Each RX filter is shown to receive an RX signal from the correspondingantenna port (ANT) (144 a, 144 b or 144 c). Such an RX signal is shownto be filtered and routed to an RX component (e.g., an LNA) for furtherprocessing.

It is typically desirable to provide impedance matching between a givenduplexer and a component that is upstream (in the TX case) or downstream(in the RX case). In the example of FIG. 6, the band switch 138 is suchan upstream component for the TX filter of the duplexer. Accordingly,matching circuits 140 a-140 c (depicted as being parts of, for example,a PI network 120) are shown to be implemented between the outputs of theband switch 138 and the respective duplexers 142 a-142 c. In someembodiments, each of such matching circuits 140 a-140 c can beimplemented as, for example, a pi-matching circuit.

Table 1 lists example values of insertion loss and efficiency for thevarious components of the ET power amplification system 110 of FIG. 6.It will be understood that the various values listed are approximatevalues.

TABLE 1 Component Insertion loss Efficiency ET Mod (112) N/A 83% PowerAmp. Assy. (114) N/A 70% to 75% (PAE) Load Transform (116) 0.5 dB to 0.7dB 85% to 89% Band Switch (118) 0.3 dB to 0.5 dB 89% to 93% PI (120) 0.3dB 93% Duplex (122) 2.0 dB 63%From Table 1, one can see that the ET power amplification system 110 ofFIG. 6 includes a significant number of loss contributors. Even if eachcomponent of the system 110 is assumed to operate at its upper limit ofefficiency, the total efficiency of the ET power amplification system110 is approximately 31% (0.83×0.75×0.89×0.93×0.93×0.63).

In the example of FIG. 7, the HV APT power amplification system 100 isdepicted as being configured to provide amplification for the same threefrequency bands as in the example ET power amplification system 110 ofFIG. 6. In a power amplifier assembly 104, three separate amplificationpaths can be implemented, such that each amplification path providesamplification for its respective frequency band. For example, the firstamplification path is shown to include a PA 168 a which receives an RFsignal from an input node 162 a through a DC-block capacitance 164 a.The amplified RF signal from the PA 168 a is shown to be routed to adownstream component through a capacitance 170 a. Similarly, the secondamplification path is shown to include a PA 168 b which receives an RFsignal from an input node 162 b through a DC-block capacitance 164 b;and the amplified RF signal from the PA 168 b is shown to be routed to adownstream component through a capacitance 170 b. Similarly, the thirdamplification path is shown to include a PA 168 c which receives an RFsignal from an input node 162 c through a DC-block capacitance 164 c;and the amplified RF signal from the PA 168 c is shown to be routed to adownstream component through a capacitance 170 c.

In some embodiments, some or all of the PAs 168 a-168 c can include, forexample, HBT PAs. It will be understood that one or more features of thepresent disclosure can also be implemented with other types of PAs. Forexample, PAs that can be operated to yield impedances that match or areclose to downstream components (e.g., by HV operation and/or throughother operating parameter(s)) can be utilized to yield one or more ofthe benefits as described herein.

In the example of FIG. 7, each PA (168 a, 168 b or 168 c) is shown to beprovided with a supply voltage VCC from a boost DC/DC converter 160through a choke inductance (166 a, 166 b or 166 c). The boost DC/DCconverter 160 is depicted as being part of an HV system 102. The boostDC/DC converter 160 can be configured to supply such a range of VCCvoltage values (e.g., about 1V to 10V), including HV ranges or values asdescribed herein. The boost DC/DC converter 160 is shown to generatesuch a high VCC voltage based on a battery voltage Vbatt.

When the PAs 168 a-168 c are operated in the foregoing manner with highVCC voltage (e.g., at about 10V), impedance Z of each PA is relativelyhigh (e.g., about 40 Ω to 50 Ω); and thus, impedance transformation isnot necessary to match with impedance associated with a downstreamcomponent. In the example of FIG. 7, each of the duplexers 174 a-174 c(depicted as being parts of a duplex assembly 108) that receives theoutput of the corresponding PA (168 a, 168 b or 168 c) is typicallyconfigured as a 50 Ω load. Accordingly, and assuming that the impedance(Z) presented by the PA (168 a, 168 b or 168 c) is about 50 Ω, animpedance transformation (such as the load transform system 116 in FIG.6) is not needed.

It is typically desirable to provide impedance matching between a givenduplexer and a component that is upstream (in the TX case) or downstream(in the RX case). In the example of FIG. 7, the PA (168 a, 168 b or 168c) is such an upstream component for the TX filter of the duplexer (174a, 174 b or 174 c). Accordingly, matching circuits 172 a-172 c (depictedas being parts of, for example, a PI network 106) can be implementedbetween the respective outputs of the PAs 168 a-168 c and the respectiveduplexers 174 a-174 c. In some embodiments, each of such matchingcircuits 172 a-172 c can be implemented as, for example, a pi-matchingcircuit.

In the example of FIG. 7, the HV operation of the PAs 168 a-168 c canresult in each of the PAs 168 a-168 c presenting an impedance Z that issimilar to the impedance of the corresponding duplexer. Since impedancetransformation is not needed in such a configuration, there is no needfor an impedance transformer (116 in FIG. 6).

It is also noted that operation of the PAs 168 a-168 c at the higherimpedance can result in much lower current levels within the PAs 168a-168 c. Such lower current levels can allow the PAs 168 a-168 c to beimplemented in significantly reduced die size(s).

In some embodiments, either or both of the foregoing features(elimination of impedance transformer and reduced PA die size) canprovide additional flexibility in power amplification architecturedesign. For example, space and/or cost savings provided by the foregoingcan allow implementation of a relatively small PA (168 a, 168 b or 168 cin FIG. 7) for each frequency band, thereby removing the need for a bandswitch system (e.g., 118 in FIG. 6). Accordingly, size, cost and/orcomplexity associated with the HV APT power amplification system 100 ofFIG. 7 can be maintained or reduced when compared to the ET poweramplification system 110 of FIG. 6, while significantly reducing theoverall loss of the power amplification system 100.

Table 2 lists example values of insertion loss and efficiency for thevarious components of the HV APT power amplification system 100 of FIG.7. It will be understood that the various values listed are approximatevalues.

TABLE 2 Component Insertion loss Efficiency HV (102) N/A 93% Power Amp.Assy. (104) N/A 80% to 82% (PAE) PI (106) 0.3 dB 93% Duplex (108) 2.0 dB63%

From Table 2, one can see that the HV APT power amplification system 100of FIG. 7 includes a number of loss contributors. However, when comparedto the ET power amplification system 110 of FIG. 6 and Table 1, twosignificant loss contributors (Load Transform (116) and Band Switch(118)) are absent in the HV APT power amplification system 100 of FIG.7. Elimination of such loss contributors is shown to remove about 1 dBin the transmit path in the example of FIG. 7 and Table 2.

Also referring to Table 2, if each component of the system 100 isassumed to operate at its upper limit of efficiency (as in the exampleof Table 1), the total efficiency of the HV APT power amplificationsystem 100 is approximately 45% (0.93×0.82×0.93×0.63). Even if eachcomponent is assumed to operate at its lower limit of efficiency, thetotal efficiency of the HV APT power amplification system 100 isapproximately 44% (0.93×0.80×0.93×0.63). One can see that in eithercase, the total efficiency of the HV APT power amplification system 100of FIG. 7 is significantly higher than the total efficiency(approximately 31%) of the ET power amplification system 110 of FIG. 6.

Referring to FIGS. 6 and 7, a number of features can be noted. It isnoted that use of the DC/DC boost converter (160 in FIG. 7) can allowelimination of one or more other power converters that may be utilizedin a PA system. For example, when operated to yield an HV supply voltage(e.g., 10 VDC), 1 Watt (10V)²/(2×50 Ω)) of RF power can be produced withno harmonic terminations.

It is further noted that a PA driven as a 50 Ω load (e.g., FIG. 7)results in a significantly lower loss per Ohm than a PA driven as a 3 0load (e.g., FIG. 6). For example, an equivalent series resistance (ESR)of 0.1 Ω has an insertion loss of about 0.14 dB when the PA is driven at3 Ω, while for the PA driven at 50 Ω, an ESR of 0.1 Ω has an insertionloss of about 0.008 dB. Accordingly, the 3 Ω PA can have a totalinsertion loss of about 4.2 dB (0.14 dB×30), while the 50 Ω PA can havea total insertion loss of about 4.0 dB (0.008 dB×500), which is stillless than the total insertion loss for the 3 Ω PA.

It is further noted that the 50 Ω PA can have a significantly highergain than the 3 Ω PA. For example, gain can be approximated asG_(M)×R_(LL); if G_(M) is similar for both cases, then the higher valueof 50 Ω yields a higher gain.

FIG. 8 shows an HV APT power amplification system 100 that can be a morespecific example of the HV APT power amplification system 100 of FIG. 7.In the example of FIG. 8, a power amplifier assembly can include alow-band (LB) power amplifier assembly 190, a mid-band (MB) poweramplifier assembly 200, and a high-band (HB) power amplifier assembly210, with some or all of PAs in such assemblies capable of beingoperated with high-voltage as described herein. The power amplifierassembly can also include other PAs that do not operate in high-voltage.For example, a 2G power amplifier assembly 220 and power amplifierassemblies 230, 232 can be operated in lower voltages.

In the example of FIG. 8, the foregoing high-voltage(s) can be providedto the LB, MB and HB power amplifier assemblies 190, 200, 210 from, forexample, a front-end power management integrated circuit (FE-PMIC) 160.In some embodiments, such an FE-PMIC can include a DC/DC boost converter(e.g., 160 in FIG. 7) as described herein.

The FE-PMIC 160 can receive a battery voltage Vbatt and generate ahigh-voltage output 182 as supply voltages (VCC) for the LB, MB and HBpower amplifier assemblies 190, 200, 210. In some embodiments, such ahigh-voltage VCC can have a value of approximately 10V, with a maximumcurrent of approximately 250 mA. It will be understood that other valuesof such high-voltage VCC and/or maximum current can also be utilized.

The FE-PMIC 160 can also generate other output(s). For example, anoutput 184 can provide bias signals for the PAs associated with the LB,MB and HB power amplifier assemblies 190, 200, 210, as well as for the2G power amplifier assembly 220. In some embodiments, such a bias signalcan have a value of approximately 4V, with a maximum current ofapproximately 50 mA. It will be understood that other values of suchbias signal and/or maximum current can also be utilized.

In the example of FIG. 8, the FE-PMIC 160 can be part of an HV system102 described herein in reference to FIG. 7. The FE-PMIC 160 can includeone or more interface nodes 180. Such interface nodes can be utilized tofacilitate, for example, control of the FE-PMIC 160.

In the example of FIG. 8, supply voltage VCC for the 2G power amplifierassembly 220 is shown to be provided (e.g., line 186) substantiallydirectly from the battery voltage Vbatt. Such Vbatt is also shown toprovide operating voltages for various switches associated with the LB,MB and HB power amplifier assemblies 190, 200, 210. In some embodiments,such Vbatt can have a value in a range of about 2.5V to 4.5V. It will beunderstood that other values of such Vbatt can also be utilized.

In the example of FIG. 8, supply voltages VCC for the power amplifierassemblies 230, 232 can be provided from a DC/DC switching regulator234.

Referring to FIG. 8, the LB power amplifier assembly 190 is shown toinclude separate PAs for eight example frequency bands B27, B28A, B28B,B20, B8, B26, B17 and B13. Each PA is shown to provide its amplified RFsignal to a corresponding duplexer. As described herein, such eight PAscan be coupled to their respective duplexers without a band selectionswitch in between.

The LB power amplifier assembly 190 is further shown to include and/orbe coupled to an input switch 192 and an output switch 196. The inputswitch 192 is shown to include two input nodes 194 a, 194 b, and eightoutput nodes corresponding to the eight PAs. In the input switch 192,the two input nodes 194 a, 194 b are shown to be switchable to a commonnode which is coupled to another common node for switching to one of theeight output nodes. The coupling between such common nodes can includean amplification element.

The output switch 196 is shown to include eight input nodescorresponding to the eight duplexers, and two output nodes 198 a, 198 b.The output switch 196 can further include inputs for receiving an outputof the 2G power amplifier assembly 220 and an output of the poweramplifier assembly 230.

It will be understood that the LB power amplifier assembly 190 caninclude different combinations of frequency bands.

Referring to FIG. 8, the MB power amplifier assembly 200 is shown toinclude separate PAs for four example frequency bands B1, B25, B3 andB4. Each PA is shown to provide its amplified RF signal to acorresponding duplexer. As described herein, such four PAs can becoupled to their respective duplexers without a band selection switch inbetween.

The MB power amplifier assembly 200 is further shown to include and/orbe coupled to an input switch 202 and an output switch 206. The inputswitch 202 is shown to include an input node 204, and four output nodescorresponding to the four PAs. In the input switch 202, the input node204 is shown to be coupled to a common node for switching to one of thefour output nodes. The coupling between such nodes can include anamplification element.

The output switch 206 is shown to include four input nodes correspondingto the four duplexers, and an output node 208. The output switch 206 canfurther include an input for receiving an output of the 2G poweramplifier assembly 220.

It will be understood that the MB power amplifier assembly 200 caninclude different combinations of frequency bands.

Referring to FIG. 8, the HB power amplifier assembly 210 is shown toinclude separate PAs for two example frequency bands B7 and B20. Each PAis shown to provide its amplified RF signal to a corresponding duplexer.As described herein, such two PAs can be coupled to their respectiveduplexers without a band selection switch in between.

The HB power amplifier assembly 210 is further shown to include and/orbe coupled to an input switch 212 and an output switch 216. The inputswitch 212 is shown to include an input node 214, and two output nodescorresponding to the two PAs. In the input switch 212, the input node214 is shown to be coupled to a common node for switching to one of thetwo output nodes. The coupling between such nodes can include anamplification element.

The output switch 216 is shown to include two input nodes correspondingto the two duplexers, and an output node 218. The output switch 216 canfurther include an input for receiving an output of the power amplifierassembly 232.

It will be understood that the HB power amplifier assembly 210 caninclude different combinations of frequency bands.

In the example of FIG. 8, the PAs of the LB, MB and HB power amplifierassemblies 190, 200, 210 can be implemented as one or more die. Forexample, such PAs can be implemented on a single HBT (e.g., GaAs) die,on separate HBT die corresponding to the LB, MB and HB power amplifierassemblies 190, 200, 210, or some combination thereof.

In the example of FIG. 8, each of the input switches 192, 202, 212 canbe configured to provide switching functionalities as described herein,as well as to facilitate biasing functionalities as described herein. Insome embodiments, the switches 192, 196, 202, 206, 212, 216 can beimplemented on, for example, a single silicon-on-insulator (SOI) die, onseparate die corresponding to the various functional groups, or somecombination thereof.

FIG. 9 shows example efficiency plots as a function of output power, forpower amplifiers operated in 78% Buck ET, 97% Buck APT, and 87% BoostAPT configurations. It is noted that all three of the exampleconfigurations yield a similar efficient efficiency profile up to about15 dBm of output power. Beyond such an output level, one can see thatthe 87% Boost APT configuration has significantly higher efficiencyvalues over both of the 97% Buck APT and 78% Buck ET configurations.Such a Boost APT configuration can be implemented in either or both ofthe example HV APT power amplification systems of FIGS. 7 and 8.

FIG. 10 shows that a power amplification system (e.g., HV APT poweramplification system 100 of FIG. 8) having one or more features asdescribed herein can have collector efficiency and power-addedefficiency (PAE) profiles that are similar to nominal cases. Forexample, collector efficiency plots (as a function of output power)associated with the HV APT power amplification system of FIG. 8 areshown to have substantially same profiles as those of respective nominalcollector efficiencies. Similarly, PAE plots (as a function of outputpower) associated with the HV APT power amplification system of FIG. 8are shown to have substantially same profiles as those of respectivenominal PAEs.

FIG. 11 shows that a power amplification system (e.g., HV APT poweramplification system 100 of FIG. 8) having one or more features asdescribed herein can have linearity performance (e.g., adjacent-channelleakage ratio (ACLR)) that is similar to a nominal case. For example,ACLR plots (as a function of output power) associated with the HV APTpower amplification system of FIG. 8 are shown to have substantiallysame profiles as those of respective nominal ACLRs at higher outputpower values (e.g., higher than 29 dBm).

FIG. 12 shows example plots of power amplifier load current as afunction of load voltage for power amplifier configurations indicated as“R99” and “50RB LTE.” Suppose that a relatively low current condition of40 mA is desired for the power amplifier configurations. For example,such a current of 40 mA can result from subtracting fixed bias currentand quiescent current from the supply current (load current in FIG. 12).For the 50RB LTE example in FIG. 12, a load current of approximately 104mA can yield such a low current (40 mA) condition for the poweramplifier configuration. Such a load current of 104 mA corresponds to aload voltage (VCC) of approximately 9.5V, as indicated by point 250.Accordingly, one can see that a high-voltage power amplifier operatingconfiguration as described herein can yield a relatively low currentcondition for the power amplifier.

Examples of Advantageous Features:

FIGS. 13-16 show examples of advantageous benefits that can be obtainedin HV APT power amplification systems having one or more features asdescribed herein. As described herein, FIG. 13 shows that in someembodiments, a power amplification system 100 can include a poweramplifier (PA) configured to receive a radio-frequency (RF) signal(RF_in) at an input node 260. Such a PA can be provided with a supplyvoltage of Vcc, and such a supply voltage can include a high-voltage(HV) value as described herein. The amplified RF signal can be output asRF_out, and be routed to a filter that is configured to condition theamplified RF signal and yield a filtered signal at an output node 262.The PA can be operated (e.g., in an HV mode) to be driven atapproximately a characteristic load impedance of the filter. Such acharacteristic load impedance of the filter can be, for example,approximately 50 Ohms.

In some embodiments, the foregoing configuration can be implemented inan average-power tracking (APT) PA system so as to yield one or moreadvantageous features. For example, a less complex supply configuration,reduced loss, and improved efficiency can be realized. In anotherexample, the foregoing PA, a die having the foregoing poweramplification system 100, and/or a module having the foregoing poweramplification system 100 can be implemented in as a reduced-sizeddevice. In some embodiments, such reduced-sized device can be realizedat least in part due to elimination of some or all of the PA's outputmatching networks (OMNs) in a power amplification system.

FIG. 14 shows an example of a power amplification system 100 in which anoutput matching network (OMN) (also referred to herein as an impedancetransformation circuit) associated with a PA is substantially eliminatedbetween the PA and a filter. In the example of FIG. 14, the PA, itssupply voltage Vcc, and the filter can be configured and operatedsimilar to the example of FIG. 14. Such a PA configuration can includean HV mode of operation as described herein.

In the example of FIG. 14, some or all of the power amplification system100 can be implemented on a device 270 such as a PA die or a PA module.With the foregoing elimination of the OMN, dimensions (e.g., d1×d2)associated with the device 270 can be reduced. Further, otheradvantageous features such as reduced loss and improved efficiency canalso be realized with the elimination of the OMN.

FIG. 15 shows an example of a power amplification system 100 configuredto process RF signals for a plurality of bands. Such bands can be, forexample, Band A and Band B. It will be understood that other numbers ofbands can be implemented for the power amplification system 100.

In the example of FIG. 15, each band is shown to have associated with ita separate amplification path. In each amplification path, its PA,supply voltage Vcc, and filter can be configured and operated similar tothe example of FIG. 14. Such a PA configuration can include an HV modeof operation as described herein.

In the example of FIG. 15, each band having its own dedicatedamplification path can allow elimination of a band selection switch.Accordingly, a device 270 (such as a PA die or a PA module) having someor all of the power amplification system 100 can have reduced dimensions(e.g., d3×d4). Further, other advantageous features such as reduced lossand improved efficiency can also be realized with the elimination of theband selection switch.

FIG. 16 shows an example of a power amplification system 100 configuredto process RF signals for a plurality of bands, similar to the exampleof FIG. 15. In the example of FIG. 16, each of some or all of theplurality of amplification path can be substantially free of an outputmatching network (OMN) (also referred to herein as an impedancetransformation circuit), similar to the example of FIG. 14. Accordingly,a device 270 (such as a PA die or a PA module) having some or all of thepower amplification system 100 can have reduced dimensions (e.g.,d5×d6). Further, other advantageous features such as reduced loss andimproved efficiency can also be realized with the elimination of theband selection switch and some or all of the OMNs.

In the examples of FIGS. 15 and 16, the device 270 on which itsrespective power amplification system 100 is implemented can be, forexample, a power amplifier die having a semiconductor substrate. Theplurality of PAs can be implemented in parallel as shown on thesemiconductor substrate, and each PA can be configured to drive anindividual narrow frequency band signal path. Thus, each PA can be sizedsmaller than a wide band PA capable of driving more than one of thefrequency bands associated with the plurality of PAs. As describedherein, use of such miniaturized single-band PAs can yield a number ofdesirable features.

Examples of Products:

FIG. 17 shows that in some embodiments, some or all of an HV APT poweramplification system having one or more features as described herein canbe implemented in a module. Such a module can be, for example, afront-end module (FEM). In the example of FIG. 17, a module 300 caninclude a packaging substrate 302, and a number of components can bemounted on such a packaging substrate. For example, an FE-PMIC component102, a power amplifier assembly 104, a match component 106, and aduplexer assembly 108 can be mounted and/or implemented on and/or withinthe packaging substrate 302. Other components such as a number of SMTdevices 304 and an antenna switch module (ASM) 306 can also be mountedon the packaging substrate 302. Although all of the various componentsare depicted as being laid out on the packaging substrate 302, it willbe understood that some component(s) can be implemented over or underother component(s).

In some implementations, a power amplification system having one or morefeatures as described herein can be included in an RF device such as awireless device. Such a power amplification system can be implemented inthe wireless device as one or more circuits, as one or more die, as oneor more packaged modules, or in any combination thereof. In someembodiments, such a wireless device can include, for example, a cellularphone, a smart-phone, a hand-held wireless device with or without phonefunctionality, a wireless tablet, etc.

FIG. 18 depicts an example wireless device 400 having one or moreadvantageous features described herein. In the context of a modulehaving one or more features as described herein, such a module can begenerally depicted by a dashed box 300, and can be implemented as, forexample, a front-end module (FEM).

Referring to FIG. 18, power amplifiers (PAs) 420 can receive theirrespective RF signals from a transceiver 410 that can be configured andoperated to generate RF signals to be amplified and transmitted, and toprocess received signals. The transceiver 410 is shown to interact witha baseband sub-system 408 that is configured to provide conversionbetween data and/or voice signals suitable for a user and RF signalssuitable for the transceiver 410. The transceiver 410 can also be incommunication with a power management component 406 that is configuredto manage power for the operation of the wireless device 400. Such powermanagement can also control operations of the baseband sub-system 408and the module 300.

The baseband sub-system 408 is shown to be connected to a user interface402 to facilitate various input and output of voice and/or data providedto and received from the user. The baseband sub-system 408 can also beconnected to a memory 404 that is configured to store data and/orinstructions to facilitate the operation of the wireless device, and/orto provide storage of information for the user.

In the example wireless device 400, outputs of the PAs 420 are shown tobe matched (via respective match circuits 422) and routed to theirrespective duplexers 424. In some embodiments, the match circuit 422 canbe similar to the example matching circuits 172 a-172 c described hereinin reference to FIG. 7. As also described herein in reference to FIG. 7,the outputs of the PAs 420 can be routed to their respective duplexers424 without impedance transformation (e.g., with load transformation 116in FIG. 6) when the PAs 420 are operated in an HV mode with HV supply.Such amplified and filtered signals can be routed to an antenna 416through an antenna switch 414 for transmission. In some embodiments, theduplexers 424 can allow transmit and receive operations to be performedsimultaneously using a common antenna (e.g., 416). In FIG. 18, receivedsignals are shown to be routed through the duplexers 424 to “Rx” pathsthat can include, for example, one or more low-noise amplifiers (LNAs).

In the example of FIG. 18, the foregoing HV supply for the PAs 420 canbe provided by an HV component 102. Such an HV component can include,for example, a boost DC/DC converter as described herein.

A number of other wireless device configurations can utilize one or morefeatures described herein. For example, a wireless device does not needto be a multi-band device. In another example, a wireless device caninclude additional antennas such as diversity antenna, and additionalconnectivity features such as Wi-Fi, Bluetooth, and GPS.

As described herein, one or more features of the present disclosure canprovide a number of advantages when implemented in systems such as thoseinvolving the wireless device of FIG. 18. For example, significantcurrent drain reduction can be achieved through an elimination orreduction of output loss. In another example, lower bill of materialscount can be realized for the power amplification system and/or thewireless device. In yet another example, independent optimization ordesired configuration of each supported frequency band can be achieveddue to, for example, separate PAs for their respective frequency bands.In yet another example, optimization or desired configuration of maximumor increased output power can be achieved through, for example, a boostsupply voltage system. In yet another example, a number of differentbattery technologies can be utilized, since maximum or increased poweris not necessarily limited by battery voltage.

One or more features of the present disclosure can be implemented withvarious cellular frequency bands as described herein. Examples of suchbands are listed in Table 3. It will be understood that at least some ofthe bands can be divided into sub-bands. It will also be understood thatone or more features of the present disclosure can be implemented withfrequency ranges that do not have designations such as the examples ofTable 3.

TABLE 3 Tx Frequency Rx Frequency Band Mode Range (MHz) Range (MHz) B1FDD 1,920-1,980 2,110-2,170 B2 FDD 1,850-1,910 1,930-1,990 B3 FDD1,710-1,785 1,805-1,880 B4 FDD 1,710-1,755 2,110-2,155 B5 FDD 824-849869-894 B6 FDD 830-840 875-885 B7 FDD 2,500-2,570 2,620-2,690 B8 FDD880-915 925-960 B9 FDD 1,749.9-1,784.9 1,844.9-1,879.9 B10 FDD1,710-1,770 2,110-2,170 B11 FDD 1,427.9-1,447.9 1,475.9-1,495.9 B12 FDD699-716 729-746 B13 FDD 777-787 746-756 B14 FDD 788-798 758-768 B15 FDD1,900-1,920 2,600-2,620 B16 FDD 2,010-2,025 2,585-2,600 B17 FDD 704-716734-746 B18 FDD 815-830 860-875 B19 FDD 830-845 875-890 B20 FDD 832-862791-821 B21 FDD 1,447.9-1,462.9 1,495.9-1,510.9 B22 FDD 3,410-3,4903,510-3,590 B23 FDD 2,000-2,020 2,180-2,200 B24 FDD 1,626.5-1,660.51,525-1,559 B25 FDD 1,850-1,915 1,930-1,995 B26 FDD 814-849 859-894 B27FDD 807-824 852-869 B28 FDD 703-748 758-803 B29 FDD N/A 716-728 B30 FDD2,305-2,315 2,350-2,360 B31 FDD 452.5-457.5 462.5-467.5 B33 TDD1,900-1,920 1,900-1,920 B34 TDD 2,010-2,025 2,010-2,025 B35 TDD1,850-1,910 1,850-1,910 B36 TDD 1,930-1,990 1,930-1,990 B37 TDD1,910-1,930 1,910-1,930 B38 TDD 2,570-2,620 2,570-2,620 B39 TDD1,880-1,920 1,880-1,920 B40 TDD 2,300-2,400 2,300-2,400 B41 TDD2,496-2,690 2,496-2,690 B42 TDD 3,400-3,600 3,400-3,600 B43 TDD3,600-3,800 3,600-3,800 B44 TDD 703-803 703-803

In the description herein, references are made to various forms ofimpedance. For example, a PA is sometimes referred to as driving a loadimpedance of a downstream component such as a filter. In anotherexample, a PA is sometimes referred to as having an impedance value. Forthe purpose of description, it will be understood that suchimpedance-related references to a PA may be used interchangeably.Further, an impedance of a PA can include its output impedance as seenon the output side of the PA. Accordingly, such a PA being configured todrive a load impedance of a downstream component can include the PAhaving an output impedance that is approximately same as the loadimpedance of the downstream component.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise,” “comprising,” and thelike are to be construed in an inclusive sense, as opposed to anexclusive or exhaustive sense; that is to say, in the sense of“including, but not limited to.” The word “coupled”, as generally usedherein, refers to two or more elements that may be either directlyconnected, or connected by way of one or more intermediate elements.Additionally, the words “herein,” “above,” “below,” and words of similarimport, when used in this application, shall refer to this applicationas a whole and not to any particular portions of this application. Wherethe context permits, words in the above Description using the singularor plural number may also include the plural or singular numberrespectively. The word “or” in reference to a list of two or more items,that word covers all of the following interpretations of the word: anyof the items in the list, all of the items in the list, and anycombination of the items in the list.

The above detailed description of embodiments of the invention is notintended to be exhaustive or to limit the invention to the precise formdisclosed above. While specific embodiments of, and examples for, theinvention are described above for illustrative purposes, variousequivalent modifications are possible within the scope of the invention,as those skilled in the relevant art will recognize. For example, whileprocesses or blocks are presented in a given order, alternativeembodiments may perform routines having steps, or employ systems havingblocks, in a different order, and some processes or blocks may bedeleted, moved, added, subdivided, combined, and/or modified. Each ofthese processes or blocks may be implemented in a variety of differentways. Also, while processes or blocks are at times shown as beingperformed in series, these processes or blocks may instead be performedin parallel, or may be performed at different times.

The teachings of the invention provided herein can be applied to othersystems, not necessarily the system described above. The elements andacts of the various embodiments described above can be combined toprovide further embodiments.

While some embodiments of the inventions have been described, theseembodiments have been presented by way of example only, and are notintended to limit the scope of the disclosure. Indeed, the novel methodsand systems described herein may be embodied in a variety of otherforms; furthermore, various omissions, substitutions and changes in theform of the methods and systems described herein may be made withoutdeparting from the spirit of the disclosure. The accompanying claims andtheir equivalents are intended to cover such forms or modifications aswould fall within the scope and spirit of the disclosure.

What is claimed is:
 1. A power amplification system comprising: a poweramplifier (PA) configured to receive and amplify a radio-frequency (RF)signal; and an output filter coupled to the PA by an output path that issubstantially free of an impedance transformation circuit.
 2. The poweramplification system of claim 1 wherein the PA is further configured todrive approximately a characteristic load impedance of the outputfilter.
 3. The power amplification system of claim 2 wherein the PAbeing configured to drive approximately the characteristic loadimpedance of the output filter is effectuated by the PA being operatedwith a high-voltage (HV) supply.
 4. The power amplification system ofclaim 3 wherein the output path being substantially free of an impedancetransformation circuit results in a reduction in loss by at least 0.5 dBbetween the PA and the output filter.
 5. The power amplification systemof claim 3 wherein the PA has an impedance that is greater thanapproximately 40 Ohms.
 6. The power amplification system of claim 5wherein the impedance of the PA results in a reduced current drain inthe PA.
 7. The power amplification system of claim 3 further comprisinga supply system configured to provide a high-voltage (HV) supply to thePA.
 8. The power amplification system of claim 7 wherein the supplysystem includes a boost DC/DC converter configured to generate the HVsupply based on a battery voltage Vbatt.
 9. The power amplificationsystem of claim 8 wherein the PA includes a heterojunction bipolartransistor (HBT) implemented as a gallium arsenide (GaAs) device. 10.The power amplification system of claim 3 wherein the output filter is atransmit (Tx) filter configured to operate in a corresponding Txfrequency band.
 11. The power amplification system of claim 3 furthercomprising one or more additional PAs, each configured to operate withthe HV supply and amplify a corresponding RF signal.
 12. The poweramplification system of claim 11 further comprising an output filtercoupled to each of the one or more additional PAs by an output path thatis substantially free of an impedance transformation circuit.
 13. Thepower amplification system of claim 12 wherein each of the one or moreadditional PAs is further configured to drive approximately acharacteristic load impedance of the corresponding output filter. 14.The power amplification system of claim 13 wherein the system issubstantially free of a band selection switch between the PAs and theircorresponding output filters.
 15. The power amplification system ofclaim 14 wherein the power amplification system is configured to operateas an average power tracking (APT) system.
 16. The power amplificationsystem of claim 15 wherein the APT system has a lower loss than anotherpower amplifier system having similar band handling capability but inwhich the PAs are operated in low voltage.
 17. A wireless devicecomprising: a transceiver configured to generate a radio-frequency (RF)signal; a front-end module (FEM) in communication with the transceiver,the FEM including a packaging substrate configured to receive aplurality of components, the FEM further including a power amplificationsystem implemented on the packaging substrate, the power amplificationsystem including a plurality of power amplifiers (PAs), each PAconfigured to receive and amplify a radio-frequency (RF) signal, thepower amplification system further including an output filter coupled toeach of the PAs by an output path that is substantially free of animpedance transformation circuit; and an antenna in communication withthe FEM, the antenna configured to transmit the amplified RF signal. 18.A method for processing a radio-frequency (RF) signal, the methodcomprising: amplifying the RF signal with a power amplifier (PA);routing the amplified RF signal to an output filter substantiallywithout impedance transformation; and filtering the amplified RF signalwith the output filter.
 19. The method of claim 18 wherein amplifyingthe RF signal includes operating the PA such that the PA drivesapproximately a characteristic impedance of the output filter to allowthe routing substantially without the impedance transformation.
 20. Themethod of claim 18 wherein operating the PA includes supplying the PAwith a high-voltage (HV).